The provisions of the 2010 Patient Protection and Affordable Care Act take a decade to be come into effect. If Barack Obama wins a second term, his signature legislation will still not be fully implemented until four years after he leaves office. But key provisions are already in place.

The reforms are so broad that they cover measures ranging from the manufacture of generic drugs to a requirement for restaurants to include calorie counts on menus. But at the core are provisions intended to make healthcare more affordable and accessible, including insuring up to 50 million Americans who are presently without coverage.

The central plank of the legislation is the individual mandate. The court may decide to strike that down alone and keep the other provisions, or they may throw out the entire law. Here are the main provisions.

In force now

• Within weeks of the law being passed in 2010, regulations kicked in giving immediate access to health insurance for people with pre-existing medical conditions who had previously been refused coverage.

• Insurance companies were also prohibited from refusing to insure young people under the age of 19 with preexisting medical conditions.

• Insurers were also banned from what were widely regarded as immoral practices, such as cancelling policies when the holders became sick, and imposing lifetime financial limits on payouts for essential care, for example hospital stays. In a significant number of cases, these practices had caused people to lose their homes or go into bankruptcy to pay medical bills.

• One particularly popular early measure is a provision allowing parents to keep their dependent children on their insurance policies until the offspring are 26 years old – a move that saved many from having to take out new and expensive policies as students.

• Insurance companies must also now offer certain preventative health services without additional cost, such as mammograms.

The individual mandate

The most contentious of the reforms is scheduled to kick in on 1 January, 2014 - the requirement for almost every American to obtain health insurance. A sliding scale of penalties kicks in over the following two years, rising to 2.5% of income or $695 per person, by 2016 for those who fail to buy insurance. Expanded Medicaid coverage will provide care for those living below the poverty line.

Other 2014 measures

• The establishment of health insurance exchanges to spread the risk in order to cover the additional costs insurance companies incur through the reforms while making policies more affordable. Premiums will be subsidised for people living in households with a total income of up to four times the poverty line up to a maximum of 9.5% of income.

•The exchanges will require that people deemed to be high risk because of pre-existing medical conditions cannot be charged higher rates than the rest of the population with a cap on additional out of pocket medical expenses of $5,950 per year for individual or $11,900 for each family.